SCIM/Service Broker enable operators to add multiple applications to serve a single session. IP multimedia subsystem (IMS) Application Servers use Media Server Control Markup Language (MSCML) to play announcements over media resource functions (MRF) to subscribers. However, customized applications for mobile networks enhanced logic (CAMEL) (CAP2, CAP3, CAP4) provides a set of dedicated operations for user interaction (playing announcements, collecting digits, etc).
A common method to enable IMS applications utilizing MSCML to play announcements over a global system for mobile network (GSM) is to anchor calls, that is, to transfer the call from the IN domain to the IMS domain and then connect to the MRF. This method is not optimal as it requires additional resources, and, in some cases, requires hauling the calls from one location to the MRF location which incurs additional costs for operators.
FIGS. 1A and 1B show a sequence diagram of an example SCIM with anchoring. As shown in FIGS. 1A and 1B, APP1 100 is configured to play an announcement at the beginning of a call to the caller A 102. In this example, A 102 is connected via a GSM network and needs to be connected to a media resource function (MRF 104) in order to receive the announcement. The call is initiated at 106 with a CAMEL InitialDP message to SCIM 108. INVITE messages are exchanged 110 with APP1 100, and APP1 indicates that it needs to connect A 102 to a resource function (to play an announcement). A 102 is then connected from the mobile switching center (MSC) to a media gateway (MG) and a media gateway control (MGC 112) which convert from TDM/ISUP to RTP/SIP (IMS). At 114, an INVITE message is sent from MGC 112 to SCIM 108 which includes the correlation information from SCIM 108. SCIM sends INFO (116) to APP1 marking that a voice path has been established toward the MRF, APP1 100 sends an INFO message 118 to the SCIM 108 identifying which message should be played using MSCML. At 120, the message is played to caller A and any needed information (e.g., digits) is collected. At 122, a CAMEL disconnect forward connection message (DFC) is sent to disconnect A from the resource function and at 124 the connections to the MG and MGC 112 and MRF 104 are closed. As shown above, this method of anchoring CAMEL/TDP into IMS is inefficient, and requires substantial processing.
Additionally, some SCIM/Service Broker platforms provide IMS applications, a standard API such as JSR309 “Media Server Control API” to access IMS MRF (via MSCML) and for non IMS applications, a different API to access the CAMEL operations (this overcomes the need to Anchor calls); however, in these cases, there is a need to develop an application twice—once for IMS (SIP and MSCML) and once for CAMEL, which incurs additional costs at development time, as well as additional maintenance costs.